1. Field of the Invention
The present invention relates to novel phenoxyethylamine derivatives represented by the following general formula (I), their optical isomers, pharmacologically-acceptable acid addition salts thereof, process for preparing the same, and pharmaceutical compositions exhibiting excellent .alpha..sub.1 -blocking activity containing the same as active ingredient which can be used in the treatment of hypertension or dysuria. ##STR3##
2. Description of the Prior Art
It is already known that an .alpha..sub.1 -blocker can be used for the treatment of hypertension and a number of .alpha..sub.1 -blockers have already been marketed or developed. Recently it was found that .alpha..sub.1 -blockers affect the smooth muscle of the lower urinary tract and a new use of the .alpha..sub.1 -blockers, namely, treatment of dysuria, hypertrophy of the prostatic gland and frequency of urination is being followed with interest. The compound YM-12617[Japan Kokai 56-110665], which is an example of compounds having a structure similar to those of the present invention, is also an .alpha..sub.1 -blocker. It has the formula; ##STR4## but medicaments such as YM-12617 are not satisfactory for practical use because of insufficient efficacy and the presence of side effects.
3. Summary of the Invention
As a result of extensive investigations, it has now been found that novel phenoxyethylamine derivatives represented by the general formula (I): ##STR5## wherein R.sub.1 and R.sub.5 represent lower-alkyl, R.sub.2 and R.sub.3, which may be the same or different, each represents hydrogen or lower-alkyl, or ##STR6## represents a 5- or 6-membered ring which may be substituted and may include a nitrogen, oxygen or sulfur atom as a ring membered atom, R.sub.4 represents hydrogen or lower-alkyl and n represents an integer selected from 1 to 3, their optical isomers, and their pharmacologically-acceptable acid addition salts, exhibit excellent .alpha..sub.1 -blocking activity.
Further, according to the present invention, there are provided also a process for preparation of the novel phenoxyethylamine derivatives represented by the general formula (I), pharmaceutical compositions thereof, and a method of treating therewith.